import java.util.HashMap;

public class demo1 {
    public static void main(String[] args) {
        HashMap<Student,String> hashMap = new HashMap<>();
        Student s1 = new Student("Bob",22);
        Student s2 = new Student("Anna", 23);
        Student s3 = new Student("Jack",35);
        hashMap.put(s1,"1001");
        hashMap.put(s2,"1002");
        hashMap.put(s3,"1003");

        System.out.println(hashMap.isEmpty());
        hashMap.clear();
        System.out.println(hashMap.isEmpty());
    }
}
